Stable healing of a tendon graft to an adjacent bone is often important in tendon or ligament reconstruction. Successful incorporation of the graft is typically dependent on two factors. First, the graft should be fixed in such a way as to maximize the contact area between the graft and the bone, thereby providing the greatest amount of surface area for graft incorporation. Second, the graft fixation should be stable, minimizing the amount of motion between graft and bone. This can minimize the amount of weak fibrous tissue that forms at the bone-graft interface and maximize the degree to which a more stable bone-soft tissue interface develops at the point of bone-graft contact.
More particularly, graft fixation techniques for bone to tendon graft healing often affects the successful incorporation of the graft. One graft fixation technique is the use of an interference screw, which typically improves the pullout strength of tendon grafts. In addition, better tunnel location, tunnel compaction, tighter graft/tunnel fit, improved graft preparation/suturing techniques, and the use of longer, biodegradable screws usually further contribute to increase the pullout strengths.
However, the interference screw itself on one side of the graft can limit the bone/graft contact to a portion of the graft'circumferential area. Some studies suggest stable bony ingrowth of the graft into the surrounding bone occurs at the outer rim of the bone tunnel. With the interference screw, this ingrowth may be limited to the side of the graft that is in direct contact with bone; the other half of the graft contacts the screw and hence is not available for bony ingrowth. Thus, it is possible that there is little or no bony ingrowth where the interference screw intervenes between the tendon graft and the host bone.
In addition, spinning of the tendon graft during insertion of the interference screw may be a problem that is difficult to control once it has begun. This “tendon spin” can damage the graft and result in impingement and less-than-ideal graft positioning, possibly affecting the clinical results.
Furthermore, the benefits of tunnel and graft preparation may be negated if poor technique is used in positioning the interference screw, in which case the screw may become loose or pulled out from the bone. Therefore, positioning of the screw, such as the distance from the bone tunnel and angle of placement, may greatly affect pullout values and can undo the benefits of a properly prepared bone tunnel and/or graft.
What is desired, therefore, is a tool and method for reducing tendon spinning. Another desire is a tool and method for increasing bony ingrowth. A further desire is a tool and method for properly positioning the interference screw and reducing the dependence on the user'technique.